<template>
  <div>
    <router-link tag="div" to='/' class="header-abs" v-show="showAbs">
      <span class="iconfont back-icon header-abs-back">&#xe624;</span>      
    </router-link>
    <div class="header-fixed" v-show="!showAbs" :style="opacityStyle">
      <router-link to="/">
        <div class="header-left">
          <span class="iconfont back-icon">&#xe624;</span>
        </div>
    </router-link>
      景点详情
    </div>
  </div>
</template>

<script>
export default {
  name:'DetailHeader',
  data () {
    return {
      showAbs:true,
      opacityStyle:{
        opacity:0
      }
    }
  },
  methods: {
    handleScroll(){
      // console.log(document.documentElement.scrollTop);
      const top = document.documentElement.scrollTop;
      if (top>60) {
        let opacity = top / 140;
        opacity = opacity > 1 ? 1 : opacity;
        this.opacityStyle = {
          opacity:opacity
        }
        this.showAbs = false
      } else {
        this.showAbs = true
      }
    }
  },
  activated () {
    window.addEventListener('scroll',this.handleScroll)
  },
  deactivated () {
    window.removeEventListener('scroll',this.handleScroll)
  }
}
</script>

<style lang="stylus" scoped>
@import '~@/assets/styles/varibles.styl'

  .header-abs
    position absolute
    left .2rem
    top .2rem
    width .8rem
    height .8rem
    line-height .8rem
    border-radius .4rem
    text-align center
    background :rgba(0, 0, 0, .8)
    .header-abs-back
      color :#fff
      font-size :.4rem
  .header-fixed
    z-index :2
    position fixed
    top 0
    left 0
    right 0
    overflow :hidden
    height :.86rem
    line-height :.86rem
    text-align :center
    color :#fff
    background :$bgColoer
    font-size :.32rem
    .header-left
      position absolute
      width :0.64rem
      float: left
      .back-icon
        font-size :.1.7rem
        padding-left :.2rem
        color :#fff    
</style>
